A Study of the Silent Flight of the Owl

Many species of owl, including the barn and barred owl, use both visual and bi-aural location to search for prey around dusk and at night. Their bi-aural location system has a maximum sensitivity between 3-6kHz although the hearing of the owl has an upper limit in excess of 20kHz. Its prey, typically voles and mice, squeak and and squeal in the frequency range of 3-6kHz and this range of frequency includes the rustling of leaves made by prey. The hearing of these prey is acute between 2-20kHz. The owl in both gliding and flapping flight generates noise at low frequencies below 2kHz, but is almost totally silent at frequencies above 2kHz. Hence the flight of the owl is almost silent to its prey. When an owl attacks its prey from its perch from a height of 6-10m the prey are unaware of its approach before they are captured by its long talons.